Rolls of the type generally mentioned above, are referred to as combi rolls by those skilled in the art. In practice, such rolls are used for hot or cold rolling of long narrow products of metal, such as wires, bars, pipes, etc. For such purposes, the roll ring or rings, i.e., the very rings which, in contrast to spacer rings and the like, carry out the forming of the metals are formed with a number of circumferential grooves, usually having a semi-circular cross section shape.
An important factor for a prolonged proper function of such rolls is that the different roll and spacer rings are rotationally secured in relation to each other and in relation to the roll shaft in a reliable way, since extremely large torques are to be transferred from the shaft to the rings without the same slipping in relation to each other. To overcome this problem, tightening devices are used, which may be divided into two main categories, viz. on one hand devices, which utilize the spring force of mechanical springs, and on the other hand, hydraulically acting devices. Of these devices, the last-mentioned ones are less suitable for many reasons, e.g., the necessity to providing expensive hydraulic oil conduits to the rotating roll, the risk of oil leakage, etc. Therefore, mechanical springs are preferable, in so far that they are technically less complicated, as well as easier and more inexpensive to manufacture, install and use.
In the technique in question, many proposals of mechanical springs for combi rolls have come up. One of these proposals is disclosed in U.S. Pat. No. 5,735,788, and is based on the use of a Belleville spring in the set of dismountable rings of the roll shaft. However, this solution has not been successful, among other things dependent on the placing of the spring inside the set of roll rings and spacer rings, and because of fatigue problems. It is true that the tension or the spring force of the Belleville spring in question should be possible to readjust, viz. by way of a set screw, but as a consequence of the placing thereof inside the set of dismountable rings, the spring is continuously exposed to forces, which deform, more precisely flatten the spring, something which fairly fast results in a slackening or fatigue to such an extent that the spring looses the ability to instantaneously, during operation, keep the rings pressed against each other with such a force in the friction joints there between, that the same do not slip. Furthermore, the inclined spring wears against adjacent rings in such a way that these become worn in a fairly short time due to the fact that the spring has a (circular) line contact and not a surface contact, with the rings.